Lithium-ion secondary battery, negative electrode for lithium-ion secondary battery, battery pack, electric vehicle, power storage system, electric tool, and electronic device

Abstract

A lithium-ion secondary battery includes a positive electrode, a negative electrode containing an active material, and an electrolytic solution, in which the active material includes a core portion capable of occluding and releasing lithium ions, and a covering portion arranged on at least part of a surface of the core portion, in which the covering portion contains, as constituent elements, Si, O, and at least one element M1 selected from Li, C, Mg, Al, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Ge, Zr, Mo, Ag, Sn, Ba, W, Ta, Na, and K, and the atomic ratio y (O/Si) of O to Si is 0.5≦y≦1.8.

The invention is claimed as follows: 
     
       1. A lithium-ion secondary battery comprising:
 a positive electrode; 
 a negative electrode containing a plurality of active material particles; and 
 an electrolytic solution, wherein each of the active material particles includes:
 a core portion capable of occluding and releasing lithium ions, and 
 a covering portion arranged on at least part of a surface of the core portion, 
 
 wherein the covering portion comprises Si, O, and at least one element M1 selected from Li, C, Mg, Al, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Ge, Zr, Mo, Ag, Sn, Ba, W, Ta, Na, and K, 
 wherein an atomic ratio y (O/Si) of 0 to Si is 0.5≦y≦1.8, and 
 wherein the core portion has a median diameter of 0.3 μm to 20 μm. 
 
     
     
       2. The lithium-ion secondary battery according to  claim 1 , wherein the ratio of M1 to a total of Si and O (M1/(Si+O)) is 50 atomic percent or less. 
     
     
       3. The lithium-ion secondary battery according to  claim 1 , wherein at least one of the atoms of M1 is bonded to at least one of Si and O. 
     
     
       4. The lithium-ion secondary battery according to  claim 3 , wherein the covering portion contains a compound of Si, O, and M1. 
     
     
       5. The lithium-ion secondary battery according to  claim 1 , wherein an average coverage of the covering portion on the core portion ranges from 30% to 100%. 
     
     
       6. The lithium-ion secondary battery according to  claim 1 , wherein the covering portion has an average thickness of 1 nm to 10,000 nm. 
     
     
       7. The lithium-ion secondary battery according to  claim 1 , wherein the covering portion has a multilayer structure. 
     
     
       8. The lithium-ion secondary battery according to  claim 1 , wherein the core portion comprises at least one of Si and Sn. 
     
     
       9. The lithium-ion secondary battery according to  claim 8 , wherein the core portion comprises Si and O, and the atomic ratio x (O/Si) of O to Si is 0≦x<0.5. 
     
     
       10. The lithium-ion secondary battery according to  claim 8 , wherein:
 the core portion comprises at least one element M2 selected from the group consisting of Fe and Al, and 
 the ratio of M2 to a total of Si and O (M2/(Si+O)) ranges from 0.01 atomic percent to 50 atomic percent. 
 
     
     
       11. The lithium-ion secondary battery according to  claim 8 , wherein:
 the core portion comprises at least one element M3 selected from Cr and Ni, and 
 the ratio of M3 to a total of Si and O (M3/(Si+O)) ranges from 1 atomic percent to 50 atomic percent. 
 
     
     
       12. The lithium-ion secondary battery according to  claim 8 , wherein:
 the core portion comprises at least one element M4 selected from B, Mg, Ca, Ti, V, Mn, Co, Cu, Ge, Y, Zr, Mo, Ag, In, Sn, Sb, Ta, W, Pb, La, Ce, Pr, and Nd, and 
 the ratio of M4 to a total of Si and O (M4/(Si+O)) ranges from 0.01 atomic percent to 30 atomic percent. 
 
     
     
       13. The lithium-ion secondary battery according to  claim 1 ,
 wherein each of the active material particles includes a conductive portion arranged on at least part of a surface of the covering portion, the conductive portion having a lower electrical resistance than those of each of the core portion and the covering portion. 
 
     
     
       14. A battery pack comprising:
 the lithium-ion secondary battery according to  claim 1 ; 
 a controller configured to control the usage state of the lithium-ion secondary battery; and 
 a switching unit configured to switch the usage state of the lithium-ion secondary battery in response to an instruction from the controller. 
 
     
     
       15. An electric vehicle comprising:
 the lithium-ion secondary battery according to  claim 1 ; 
 a conversion unit configured to convert power from the lithium-ion secondary battery into a driving force; 
 a driven unit configured to be driven in response to the driving force; and 
 a controller configured to control the usage state of the lithium-ion secondary battery. 
 
     
     
       16. A power storage system comprising:
 the lithium-ion secondary battery according to  claim 1 ; 
 one or two or more electrical devices; and 
 a controller configured to control the power supply from the lithium-ion secondary battery to the electrical devices. 
 
     
     
       17. An electric tool comprising:
 the lithium-ion secondary battery according to  claim 1 ; and 
 a moving part powered by the lithium-ion secondary battery. 
 
     
     
       18. An electronic device comprising:
 the lithium-ion secondary battery according to  claim 1 , wherein the electronic device is powered by the lithium-ion secondary battery. 
 
     
     
       19. The lithium-ion secondary battery according to  claim 1 , wherein the covering portion has an average thickness of 100 nm to 10,000 nm. 
     
     
       20. The lithium-ion secondary battery according to  claim 1 , wherein the covering portion comprises granules having a median diameter of 0.3 μm to 20 μm. 
     
     
       21. A negative electrode for a lithium-ion secondary battery, the negative electrode comprising:
 a plurality of active material particles, 
 wherein each of the active material particles includes:
 a core portion capable of occluding and releasing lithium ions, and 
 a covering portion arranged on at least part of a surface of the core portion, 
 
 wherein the covering portion comprises Si, O, and at least one element M1 selected from Li, C, Mg, Al, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Ge, Zr, Mo, Ag, Sn, Ba, W, Ta, Na, and K, 
 wherein an atomic ratio y (O/Si) of O to Si is 0.5≦y≦1.8, and 
 wherein the core portion has a median diameter of 0.3 μm to 20 μm.